His bundle (H) electrograms were recorded in 15 patients with second degree atrioventricular (A-V) block and bundle branch block and these patients were prospectively followed. Site of block was proximal to H in 4 (BPH), distal to H in 4 (BDH), and undetermined in 2 (studied during 1:1 conduction). Surface electrocardiographic features were retrospectively examined to determine the value of these recordings in predicting the site of block. Patients with type I block, with or without type II or 2:1 block, had BPH. Patients with type II block, 2:1 block, or type II combined with 2:1 block had BDH. Heart failure was more common in those with BPH (3 of 4 patients as compared to 3 of 9 patients with BDH). Syncope developed more commonly in patients with BDH (6 of 9 patients) as compared to those with BPH (one of 4 patients). Permanent pacing was indicated in 3 of 4 patients with BPH, 9 of 9 patients with BDH, and one of 2 patients with block at undetermined site because of syncope or heart failure. Five of 9 patients with BDH required pacemakers within 10 days of initial admission. Most patients with second degree A-V block and bundle branch block will need permanent pacing. In patients with 2° BDH, pacemakers are indicated whether or not symptoms are present because of high risk of syncope and potential risk of sudden death. In asymptomatic patients with 2° BPH, careful observation is indicated.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)